The Global Positioning System (GPS) and other similar satellite positioning systems have enabled navigation services for mobile devices in outdoor environments. Since satellite signals may not be always reliably received and/or acquired in an indoor environment or in some particular outdoor environments, different techniques may be employed to enable position determination and related navigation services. The signals transmitted by cellular network access points (AP) can be used for positioning in such areas. Because signals from these terrestrial radio transmitters are usually available and associated with indoor structures, positioning using these signals is often used for indoor positioning. However, the systems and methods can apply to any defined region or area for which AP signals are available.
Mobile devices can typically obtain positioning information, for example, by obtaining a MAC ID address or other identifying information from signals received from APs or other terrestrial radio transmitters and by measuring one or more characteristics of signals received from such APs such as, for example, signal strength (e.g., an RSSI) and/or propagation time (e.g., a round-trip time (RTT)) for signals exchanged with various radio transmitters (e.g., APs, beacons, etc.).
In some implementations, the MAC IDs included in the AP signals can be used to identify the defined area associated with the APs and to locate the APs with respect to the defined area. Using the identification of the defined area, a mobile device may access a digital electronic map, for example, as a mobile device enters a particular defined area. Such a map may show indoor features, such as doors, hallways, entry ways, walls, etc., points of interest, such as bathrooms, room names, stores etc., as well as outdoor features such as courtyards, parking lots, yards, gardens, fencing, water features or any other outdoor structures or boundaries. Such a digital electronic map may be stored at a server to be accessible by the mobile device through the wireless network or, for example, through selection of an Internet based URL. The digital map may be available in a graphic form for display to a user of the mobile device or it may be available in a data format suitable for position calculations or other calculations done by the mobile device or the server.
The map of the defined region may be analyzed by classifying map locations as interior or exterior position points. Signal analysis may be combined with such a set of classified position points to more efficiently and accurately determine a mobile device position point solution by constraining the position point solution to certain classified position points. Combining signal analysis with such a constrained position point solution can be more efficient and accurate than position determination using signal analysis methods such as, for example, fingerprinting or triangulation methods. The determined mobile device position can be combined with the mapping information for the defined area to locate the mobile device on the defined area map for use in various applications, including navigation applications.